under the River Thames. 35 



Being informed that no particular plan has yet been de- 

 termined on by the Thames Tunnel Company *, they are 

 extremely welcome to adopt this if they think fit. 1 can- 

 not avoid encouraging a hope, that it will be found practi- 

 cable : but, should my partiality render me too sanguine in 

 favour of it, as the idea, 1 believe, is new, the publication of 

 it may lead to some other of more ingenuity, and which 

 may be easier and safer in the execution. 



Explanation of a plan for constructing a tunnel of cast- 

 iron under- the river Thames : — 



Fig. 1. A A, (Plate II.) section across the river. The 

 waving "line shows the present depth of the river; a a, the 

 additional depth required by the plan. 



Fig. 2. B B B, three of the frames of which it is pro- 

 posed that the whole tunnel shall be formed : they are to 

 be of cast-iron, each of oik- piece, and to be joined together 

 by the flanchts ddd, which are all one foot broad a;* J four 

 inches thick, with the screws eee, in figs. 2 and 4, of four 

 inches, diameter, with half-inch sheet-lead between: — or 

 the joints may be secured with the cement employed by 

 steiMii -engine builders. 



, Fig. 3. CC, section of the tunnel, showing the above 

 three frames, in figs. 2, in perspective ; each frame to be 

 ten feet in length, eighteen feet wide inside, and twelve 

 feet high at the sides; the top to be convex, rising two feet 

 in the middle; to be four inches thick at the bottom and 

 sides, and three at top. Each frame will weigh upwards of 

 forty tons t. 



Fig. 4. DDD, elevation of the same frames, which 

 shows the screws that unite the exterior flanches, and also 

 the iron cramps, fj\ which embrace the two adjoining 

 flanches at bottom ; these cramps to be each twelve inches 

 broad, six inches thick, and two feet high. 



Fig. 3. g g, tubes of eight inches bore, with openings 

 to receive leakage water, and to convey it to one o£, the 

 ends to be pumped out. 



Hi, screw- holes. 'Hie dotted line kk expresses the 

 paving when the whole is completed. 



* I believe the Thames Tunnel Company have settled the plan they mean 

 to follow ; but as the ideas suggested by Col. Lennox may prove useful oa 

 some future occasion, I have given it a place in this number. — Edit. 



+ Should the carriage of pieces of this weight from the foundry be found 

 impracticable, the side*, and top and bottom, may be cast in separate pieces, 

 with flanches to join them at the corners. In this case the joinings of the 

 different parts may be so disposed thai no two of the transverse joinings 

 ghall coincide, which will give additional strength to the whole as every 

 joint may thks be supported with three solid pieces at that place in which 

 it £alis. 



C2 By 



